Expansion of one-dimensional lattice hard-core bosons at finite temperature

TL;DR

This paper presents an exact method to analyze the quench dynamics of one-dimensional lattice hard-core bosons at finite temperature, revealing phenomena like dynamical fermionization, self-similar expansion, and temperature-dependent correlation behaviors.

Contribution

The authors develop an exact approach for studying finite-temperature quench dynamics of 1D hard-core bosons, including phenomena like dynamical fermionization and effective cooling during Mott domain melting.

Findings

Dynamical fermionization occurs at all temperatures.

Self-similar expansion observed at low initial site occupations.

Mott domain melting is accompanied by effective cooling.

Abstract

We develop an exact approach to study the quench dynamics of hard-core bosons initially in thermal equilibrium in one-dimensional lattices. This approach is used to study the sudden expansion of thermal states after confining potentials are switched off. We find that a dynamical fermionization of the momentum distribution occurs at all temperatures. This phenomenon is studied for low initial site occupations, for which the expansion of the cloud is self-similar. In this regime, the occupation of the natural orbitals allows one to distinguish hard-core bosons from noninteracting fermions. We also study the free expansion of initial Mott insulating domains at finite temperature, and show that the emergence of off-diagonal one-body correlations is suppressed gradually with increasing temperature. Surprisingly, the melting of the Mott domain is accompanied by an effective cooling of the system. We explain this phenomenon analytically using an equilibrium description based on an emergent local Hamiltonian.